An optical media storage system includes an optical pickup that unit that reads data marks from a track of optical media, detects a relative position between the optical pickup unit and the data marks, and detects a relative position between the optical pickup unit and the track. The storage system further includes an actuator and a controller that commands the actuator to position the optical pickup unit based on both of the detected relative positions.
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6. A method for controlling an optical pickup unit comprising:
detecting, by an optical pickup unit, a relative position between the optical pickup unit and data marks within a track of optical media;
generating a differential phase detection tracking signal indicative of the relative position between the optical pickup unit and the data marks;
detecting, by the optical pickup unit, a relative position between the optical pickup unit and the track;
generating a main push pull tracking signal indicative of the relative position between the optical pickup unit and the track;
filtering out frequency content of the differential phase detection tracking signal for frequencies greater than a threshold frequency;
filtering out frequency content of the main push pull tracking signal for frequencies less than the threshold frequency; and
positioning, by an actuator, the optical pickup unit based on both of the detected relative positions.
1. An optical media storage system comprising:
an optical pickup unit configured to read data marks from a track of optical media, to detect a relative position between the optical pickup unit and the data marks, to generate a differential phase detection tracking signal indicative of the relative position between the optical pickup unit and the data marks, to detect a relative position between the optical pickup unit and the track, to generate a main push pull signal indicative of the relative position between the optical pickup unit and the track, to filter out frequency content of the differential phase detection tracking signal for frequencies greater than a threshold frequency, and to filter out frequency content of the main push pull tracking signal for frequencies less than the threshold frequency;
an actuator; and
a controller programmed to command the actuator to position the optical pickup unit based on both of the detected relative positions.
11. An optical media system comprising:
an optical pickup unit including
a laser diode configured to generate a laser beam to read data marks from a track of optical media,
a plurality of detectors configured to detect data indicative of a relative position between the optical pickup unit and the data marks, and data indicative of a relative position between the optical pickup unit and the track,
circuitry configured to generate a differential phase detection tracking signal based on the data indicative of a relative position between the optical pickup unit and the data marks,
circuitry configured to generate a main push pull tracking signal based on the data indicative of a relative position between the optical pickup unit and the track,
a filter configured to filter out frequency content of the differential phase detection tracking signal greater than a threshold value,
another filter configured to filter out frequency content of the main push pull tracking signal less than the threshold value, and
circuitry configured to combine the filtered signals to generate a hybrid tracking signal.
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This disclosure relates to optical media servo systems.
Optical tape is a data storage medium. In certain examples, it can take the form of long narrow strips onto which patterns can be written and from which patterns can be read. Optical tape may facilitate higher data transfer rates, greater storage capacity, and reduced access times relative to magnetic tape. Moreover because optical tape is written and read using optical pick up units that do not touch the recording surface of the tape, it may be more durable than magnetic tape.
An optical media storage system includes an optical pickup unit, an actuator, and a controller. The optical pickup unit reads data marks from a track of optical media, detects a relative position between the optical pickup unit and the data marks, and detects a relative position between the optical pickup unit and the track. The controller commands the actuator to position the optical pickup unit based on both of the detected relative positions. The optical pickup unit may generate a differential phase detection tracking signal indicative of the relative position between the optical pickup unit and the data marks. The optical pickup unit may generate a main push pull tracking signal indicative of the relative position between the optical pickup unit and the track. The optical pickup unit may filter out frequency content of the differential phase detection tracking signal for frequencies greater than a threshold frequency and filter out frequency content of the main push pull tracking signal for frequencies less than the threshold frequency. The optical pickup unit may combine the filtered differential phase detection tracking signal and the filtered main push pull tracking signal to generate a hybrid tracking signal. The controller may command the actuator to position the optical pickup unit based on the detected relative positions according to the hybrid tracking signal. The track may be defined by land and groove. Detecting a relative position between the optical pickup unit and the track may include detecting a relative position between the optical pickup unit and edges of the land and groove. The optical media may be optical tape.
A method for controlling an optical pickup unit may include detecting a relative position between the optical pickup unit and data marks within a track of optical media, detecting a relative position between the optical pickup unit and the track, and positioning the optical pickup unit based on both of the detected relative positions. The method may further include generating a differential phase detection tracking signal indicative of the relative position between the optical pickup unit and the data marks. The method may further include generating a main push pull tracking signal indicative of the relative position between the optical pickup unit and the track. The method may further include filtering out frequency content of the differential phase detection tracking signal for frequencies greater than a threshold frequency and filtering out frequency content of the main push pull tracking signal for frequencies less than the threshold frequency. The method may further include combining the filtered differential phase detection tracking signal and the filtered main push pull tracking signal to generate a hybrid tracking signal. Positioning the optical pickup unit based on the detected relative positions may include processing the hybrid tracking signal. The track may be defined by land and groove. Detecting a relative position between the optical pickup unit and the track may include detecting a relative position between the optical pickup unit and edges of the land and groove. The optical media may be optical tape.
An optical media system includes an optical pickup unit. The optical pickup unit includes a laser diode configured to generate a laser beam to read data marks from a track of optical media, a plurality of detectors configured to detect data indicative of a relative position between the optical pickup unit and the data marks, and data indicative of a relative position between the optical pickup unit and the track, and circuitry configured to generate a differential phase detection tracking signal based on the data indicative of a relative position between the optical pickup unit and the data marks. The optical pickup unit further includes circuitry configured to generate a main push pull tracking signal based on the data indicative of a relative position between the optical pickup unit and the track, a filter configured to filter out frequency content of the differential phase detection tracking signal greater than a threshold value, another filter configured to filter out frequency content of the main push pull tracking signal less than the threshold value, and circuitry configured to combine the filtered signals to generate a hybrid tracking signal. The track may be defined by land and groove. Detecting a relative position between the optical pickup unit and the track may include detecting a relative position between the optical pickup unit and edges of the land and groove. The optical media may be optical tape.
Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
In high track-per-inch optical storage systems, reliable retrieval of data depends on the performance of associated tracking servo systems. Study of track mis-registration in these systems, which can cause performance degradation and loss of data, reveals the importance of accurately positioning the optical head over the track containing data. Present tracking servo systems for rewritable optical media position the optical head over the perceived data track based on reference tracking signals generated by the optical pickup unit according to its diffraction properties and the physical format of the media. Because these types of positioning systems typically depend entirely on reference tracking signals and not the actual location of written data, they are subject to track mis-registration due to various disturbances and anomalies, such as the misalignment between mechanical and optical subsystems or variation from optical pickup unit to optical pickup unit. Optical pickup unit to optical pickup unit variation can be particularly apparent, manifesting as track mis-registration, when media is written with one optical pickup unit and read by another.
Referring to
An optical system 18 may include, among other things, an optical pickup unit 20. The optical pickup unit 20 may include infrastructure, such as laser diodes, etc., to generate laser beam 22, quadrature photodiode integrated circuit (quad-PDIC) detectors 24, 26, 28, 30, amplifiers 32, 34, 36, 38, sum blocks 40, 42, and difference block 44. (Those of ordinary skill will recognize this configuration as main push pull (MPP) or radial push pull tracking infrastructure 45. The phrase “main push pull” is typically used within the context of optical tape or optical disk media. The phrase “radial push pull” is typically used within the context of disk media. From a conceptual standpoint, these phases can be used interchangeably.)
Output from the detectors 24, 26, 28, 30, which is indicative of the position of the edges 16 relative to the optical pick up unit 20, is fed to the amplifiers 32, 34, 36, 38 respectively. Output from the amplifiers 32, 34 is fed to the sum block 40. Output from the amplifiers 36, 38 is fed to the sum block 42. Output from the sum blocks 40, 42 is fed to the difference block 44. The resulting output can be referred to as a MPP or radial push pull tracking signal.
The shape of a MPP signal reflects the relative movement between the edges 16 and optical pick up unit 20. A MPP signal having the shape of a horizontal line, for example, would indicate that the laser beam 22 is centered between the edges 16. A MPP signal having the shape of a sinusoid, for example, would indicate that the laser beam 22 is moving relative to the edges 16.
Referring to
An optical system 50 may include, among other things, an optical pickup unit 52. The optical pickup unit 52 may include infrastructure, such as diodes, etc., to generate laser beam 54, quad-PDIC detectors 56, 58, 60, 62, amplifiers 64, 66, 68, 70, sum blocks 72, 74, filters 76, 78, comparators 80, 82, phase detector 84, filters 86, 88, and differential amplifier 90. (Those of ordinary skill will recognize this configuration as differential phase detection (DPD) tracking infrastructure 91.)
Output from the detectors 56, 58, 60, 62, which is indicative of the relative position between the data marks 48 and optical pick up unit 52, is fed to the amplifiers 64, 66, 68, 70 respectively. Output from the amplifiers 64, 68 is fed to the sum block 72. Output from the amplifiers 66, 70 is fed to the sum block 74. Output from the sum block 72 follows a path through the filter 76, comparator 80, phase detector 84, and filter 86 to the differential amplifier 90. Likewise, output from the sum block 74 follows a path through the filter 78, comparator 82, phase detector 84, and filter 88 to the differential amplifier 90. The resulting output can be referred to as a DPD tracking signal.
The shape of a DPD signal reflects the relative movement between the data marks 48 and optical pick up unit 52. A DPD signal having the shape of a horizontal line, for example, would indicate that the laser beam 54 is centered on the data marks 48. A DPD signal having the shape of saw teeth, for example, would indicate that the laser beam 54 is moving relative to the data marks 48.
Referring to
An optical system, such as the optical system 18 of
Referring to
Referring to
The optical pickup unit 104 may include infrastructure, such as diodes, etc., to generate laser beam 110, quad-PDIC detectors 112, 114, 116, 118, sum block 120, MPP tracking infrastructure 122, high pass filter 124, DPD tracking infrastructure 126, low pass filter 128, and sum block 130. The MPP tracking infrastructure 122 is similar to the MPP tracking infrastructure 45 of
During a write operation (see
During a read operation (see
Referring to
The offset in data marks 100 relative to the center of the groove 96 can be captured in the low frequency content associated with the DPD tracking signal because of the “DC” and low frequency nature of such offsets. Because the magnitude of such offsets is relatively constant over extended sections of media, high-frequency content is not needed to capture it. Lateral motion of the optical tape 92, on the other hand, can be relatively erratic and therefore best captured in the high-frequency content associated with the MPP tracking signal. That is, low frequency content of the MPP tracking signal is not needed to capture relative movement between the edges 98 and laser beam 110.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. Tracking techniques other than DPD and MPP, for example, may be used. Any tracking technique that can capture data indicative of the relative position between an optical pickup unit and data marks being read by the optical pickup unit may be used. Likewise, any tracking technique, such as Differential Push Pull, that can capture data indicative of the relative position between an optical pickup unit and some physical characteristic of the optical media being read by the optical pickup unit may be used. Additionally, filtering techniques other than high and low pass filtering techniques, such as discriminating or matched filter techniques, can be used to process the data indicative of the relative position of the optical pickup unit to the data marks and physical characteristics of the optical media as desired, etc.
The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and can be desirable for particular applications.
Patent | Priority | Assignee | Title |
9142236, | Sep 30 2014 | Oracle International Corporation | H-bridge power amplifier for optical recording head actuator |
9336812, | Jan 09 2015 | Oracle International Corporation | Adaptive control of tracking servo system of optical heads in optical storage devices |
Patent | Priority | Assignee | Title |
7164630, | Jan 31 2002 | Kabushiki Kaisha Toshiba | Optical disk apparatus |
7609599, | Feb 17 2006 | MEDIATEK INC. | Method of identifying a type of an optical disc and the device therefor |
7916598, | Apr 24 2009 | Sunplus Technology Co., Ltd. | Method for determining type of disk and apparatus thereof |
8134909, | Jul 10 2007 | Sharp Kabushiki Kaisha | Optical information storage medium, optical information storage medium playback apparatus, method of controlling optical information storage medium playback apparatus, control program of optical information storage medium playback apparatus, and storage medium storing the program therein |
20070076546, | |||
20080151722, | |||
20110158070, |
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